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E. M. Kellogg (SAO), J. M. Hollis, J. A. Pedelty, R. G. Lyon (GSFC)
R Aqr is a symbiotic star system, a Mira-type mass-losing variable with a possible WD or hot subdwarf companion, inferred from a hot nebular emission spectrum. The system also contains an astrophysical jet, believed to be the closest to the Earth.
Detection of X-rays from R Aqr was reported in an Einstein observation, then questioned after reanalysis. Detection was again reported with EXOSAT. A serendipitous ROSAT PSPC pointed observation, not previously reported in the literature, was done on 1992 Dec 20. An X-ray source is clearly visible in the data, and an excess at that location can be seen in the ROSAT All Sky Survey. Here we report an X-spec analysis of the PSPC data. A good fit is obtained to a Raymond model, with kT = 0.1 ±0.2 keV, and nH = (2.8 ±1.5) \times 1020 cm-2, in agreement with the \emph{Colden} value. The significance of the derived temperature is discussed.
The ROSAT HRI also detected X- ray emission from R Aqr in 1994 June. The ROSAT HRI did not have the spatial resolution to determine whether the emission comes from a hot gas in either the jet or possibly the accretion disk that surrounds the hot companion.
We will learn much more about R Aqr when we obtain the Chandra/ACIS X-ray data - whether there is low energy X-ray absorption, either local or by intervening interstellar matter.
We may identify emission lines and spatially resolve the X-ray source, which may be associated with the accretion disk or the shocked jet as seen with HST and VLA. If our scheduled CHANDRA observation of R Aqr is completed by the time this work is presented, those results may be included as well.
E. K. gratefully acknowledges support by the National Aeronautics & Space Administration, contract NAS8-39073 and grant GO0-1062A.